Pairing Security, Fault Tolerance

Wednesday, May 23, 2012 @ 04:05 PM gHale

By Oliver Kleineberg
There is a need for improved cyber security for industrial networks, all security professionals know this. After all, the whole industrial automation world was stunned by the sudden appearance of Stuxnet in 2010.

Besides this targeted need, however, there is another reason why the latest cyber security technologies are needed. That reason is the broader need for reliable networks used in mission-critical applications.

Let’s look at the stunning number of places where Industrial Ethernet sees use in today’s society, often hidden in plain view. For example, in things you may come across or interact with on a daily basis, such as traffic lights. You likely don’t think “Industrial Ethernet” when stopped at a red light. That is a good thing, because it means that the Ethernet and IP technology is getting the job done properly. If it wasn’t you would certainly have already noticed.

The reliability of traffic systems is mostly due to the fact the switches used are designed for rugged environments, e.g. with a wide range of operating temperatures and with special resistance to strong electromagnetic fields or vibration. This is very different to the switches you can buy at an electronics store for your home network.

In addition to that, the switches also implement special redundancy protocols that help to recover from errors in the network, e.g. the Parallel Redundancy Protocol (PRP) or the Media Redundancy Protocol (MRP). If, for example, an excavator accidentally damages a cable, the switches will automatically compensate. Great, but what does this have to do with security?

In a nutshell, industrial ruggedized networks are tough to bring down. But remember the story of David and Goliath? Even the strongest giant can be defeated with just a small pebble, if it is used correctly. That is where cyber security comes into play.

When I talk to experts who design mission-critical networks, e.g. for power utility or industrial automation systems, fault tolerance and security are usually addressed independently. Totally separate solutions end up developed and implemented. Since fault tolerance is generally used to increase the resilience of the network, and security is usually implemented to prevent unauthorized network access, this seems to be a prudent course of action. Or is it?

Implementing fault tolerant networks increases the total network availability because the network can automatically reconfigure to compensate for media or device failure. Security increases the total network availability because it protects from any downtime caused by a cyber attack or network incident.

In addition to that, security technology protects redundant systems from attackers tampering with their protocols and the redundancy technology assures secure systems are still available, even after physical failure or a physical attack.

In the future, network architects will have to rethink their traditional design approach because security and fault-tolerance are interdependent elements of high availability networks.

Plus, just like how good food paired with the right wine brings out the sublime quality of both, a design paradigm that includes both elements takes high availability mission-critical networks to a whole new level.

Are you a forward thinking network engineer designing mission-critical networks for both high redundancy and high security?

Oliver Kleineberg joined Tofino Security from sister company Hirschmann, based in Germany (and both of groups are part of Belden). Click here to read the full version of the Practical SCADA Security blog. Kleineberg is involved with standards groups at IEEE like IEEE 802.1 and 802.3. In particular he is working with the IEC SC65C WG15 high availability automation networks working group.